[s-cars] While we are on the subject of WGFVs...

[Mark Strangways]

I undo my post, I can't read or type tonight... I'm taking my toys and going 
home !

:-)

Mark S
----- Original Message ----- 
From: "Mark Strangways" <Strangconst at rogers.com>
To: <s-car-list at audifans.com>
Sent: Wednesday, January 11, 2006 8:23 PM
Subject: Re: [s-cars] While we are on the subject of WGFVs...


>I kinda don't see it that way.
>
> I always felt that the wastegate would only see boost when the WGFV is 
> open or energized, otherwise it see the "vacuum" stream on the inlet side 
> of the compressor. I am not 100% convinced that there is enough vacuum 
> generated to do much good.
> That has been discussed to death in previous emails, and I ain't going 
> there with out proper ammo :-)
>
> Mark S
> ----- Original Message ----- 
> From: "Theodore Chen" <tedebearp at yahoo.com>
> To: <Djdawson2 at aol.com>; <bob at chips-ur-s.com>; <s-car-list at audifans.com>
> Sent: Wednesday, January 11, 2006 8:15 PM
> Subject: Re: [s-cars] While we are on the subject of WGFVs...
>
>
>> dave,
>>
>> are you sure that's how it works on the UrS4/S6?
>>
>> i agree with your description of the configuration, but
>> note that the WGFV is plumbed to the lower chamber of the
>> wastegate.
>>
>> the WGFV has three ports on it.  the left port goes to the
>> wastegate.  the right port goes to the turbo intake.  the
>> bottom port goes to the turbo output.  normally, the
>> bottom port is connected to the left port and air can pass
>> freely.  normally, the bottom port is not connected to the
>> right port and air cannot pass between these two ports.
>> when the WGFV is actuated, all three ports are connected
>> to each other.  i verified this by applying 12v to the WGFV
>> and blowing through each of the ports.
>>
>> the way the wastegate is plumbed on the UrS4 is that boost
>> is used to open the wastegate.  if the ECU wants more boost,
>> the ECU implements this by actuating the WGFV, thereby bleeding
>> boost off into the intake.  if the ECU never actuates the
>> WGFV, all the boost from the turbo goes to the wastegate
>> and the wastegate will open at the default pressure.
>>
>> --- Djdawson2 at aol.com wrote:
>>
>>> FWIW...
>>> The WGFV is basically a switch used to control the boost level at which 
>>> the
>>> WG will open.  It is also used to "increase" or "decrease"  the 
>>> strength of
>>> the WG spring when required.
>>>
>>> There are 3 ports on the WGFV.  1 of the ports goes to the  wastegate, 
>>> and
>>> basically is the means by which the ECU's desires are  communicated to 
>>> the
>>> WG.
>>> The other 2 ports provide the ECU the mechanical  means to either
>>> "strengthen"
>>> or "weaken" the wastegate spring.  1 of those  2 ports goes to vacuum, 
>>> found
>>> at the turbo inlet.  The other 1 goes to  boost, found on the scroll of 
>>> the
>>> turbo's compressor housing.
>>>
>>> If the ECU decides that all conditions are good for high boost 
>>> operation,
>>> the WGFV allows the vacuum source to pass through it to the WG, and this
>>> effectively increases the WG's ability to remain closed.  Net result... 
>>> the
>>> WG
>>> remains closed to a higher boost level than would be attainable with the
>>> spring
>>> alone.
>>>
>>> If the ECU decides that conditions are not good for high boost 
>>> operation,
>>> the WGFV begins to cycle the boost port open, allowing boost to pass 
>>> through
>>> it
>>> to the WG, and this effectively decreases the WG's ability to remain 
>>> closed.
>>>
>>>  Net result... the WG remains closed to a lower boost level than  would 
>>> be
>>> attainable with the spring alone.
>>>
>>> If you take the ECU out of the picture by removing the WGFV, or
>>> disconnecting the line to the WG, you will find that the stock WG spring 
>>> will
>>>  allow about
>>> 14-15psi of boost.  If you are running a header, you will  discover that 
>>> a
>>> stock WG spring is capable of holding the WG shut up to 25-28psi  of 
>>> boost.
>>> This can only be due to the fact that the exhaust restriction,  and 
>>> therefore
>>> the
>>> pressure built up between the cylinder head and the  turbine, is greatly
>>> reduced.
>>>
>>> Hope that helps,
>>> Dave
>>>
>>
>>
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